SLURRY COMPOSITION FOR FLEXIBLE ELECTRODE IN SECONDARY BATTERY
Provided is a slurry composition that can be used in manufacturing an electrode of a lithium-ion battery. The slurry composition comprises a binder, a solvent, an electrode active material, and an additive. The additive can be a compound described by the general formula (1). The binder is a copolymer comprising of one or more hydrophilic structural units and one or more hydrophobic structural units. The addition of the additive improves electrode flexibility significantly. A method to produce electrodes using this slurry is also disclosed. In addition, battery cells containing the electrode prepared using the slurry composition disclosed herein exhibit exceptional electrochemical performance.
1 . An electrode for a secondary battery, comprising a current collector and an electrode layer coated on one or more surfaces of the current collector, wherein the electrode layer comprises an electrode active material, a binder and an additive, wherein the additive satisfies general formula (1).
2 . The electrode of claim 1 , wherein the additive has a number-average molecular weight from about 1,000 to about 5,000 and a hydrophile-lipophile balance number from about 3 to about 13.
3 . The electrode of claim 1 , wherein a and c are independently from about 2 to about 130, and b is from about 10 to about 70.
4 . The electrode of claim 1 , wherein a and c are the same.
5 . The electrode of claim 1 , wherein the proportion of each of the repeating units α and γ is independently from about 1% to about 40% by weight, based on the total weight of the additive.
6 . The electrode of claim 1 , wherein the thickness of the electrode layer on the current collector is from about 5 μm to about 120 μm, and wherein the surface density of the electrode layer on the current collector is from about 1 mg/cm 2 to about 60 mg/cm 2 .
7 . The electrode of claim 1 , wherein the electrode active material is a cathode active material selected from the group consisting of Li 1+x Ni a Mn b Co c Al (1−a−b−c) O 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.4 Mn 0.4 Co 0.2 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.7 Mn 0.15 Co 0.15 O 2 , LiNi 0.7 Mn 0.1 Co 0.2 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.92 Mn 0.04 Co 0.04 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 , LiFePO 4 , LiCoPO 4 , LiNiPO 4 , LiMnPO 4 , LiMnFePO 4 , LiMn d Fe (1−d) PO 4 , dLi 2 MnO 3 .(1−d)LiMO 2 , LiNi e Mn f O 4 , Li 3 V 2 (PO 4 ) 3 , LiVPO 4 F, Li 2 MSiO 4 and combinations thereof; wherein −0.2≤x≤0.2, 0≤a<1, 0≤b<1, 0≤c<1, a+b+c≤1, 0<d<1, 0.1≤e≤0.9, 0≤f≤2 and M is selected from the group consisting of Fe, Co, Mn, Ni, and combinations thereof.
8 . The electrode of claim 1 , wherein the electrode active material is a cathode active material that comprises or is a core-shell composite comprising a core and a shell, wherein the core and the shell independently comprises a lithium transition metal oxide selected from the group consisting of Li 1+x Ni a Mn b Co c Al (1−a−b−c) O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 , LiFePO 4 , LiCrO 2 , Li 4 Ti 5 O 12 , LiV 2 O 5 , LiTiS 2 , LiMoS 2 , LiCo a Ni b O 2 , LiMn a Ni b O 2 , and combinations thereof, wherein −0.2≤x≤0.2, 0≤a<1, 0≤b<1, 0≤c<1, and a+b+c≤1.
9 . The electrode of claim 1 , wherein the electrode active material is an anode active material selected from the group consisting of natural graphite particulate, synthetic graphite particulate, Sn (tin) particulate, Li 4 Ti 5 O 12 particulate, Si (silicon) particulate, Si—C composite particulate, and combinations thereof.
10 . The electrode of claim 1 , wherein the binder comprises a copolymer, wherein said copolymer comprises one or more hydrophilic structural units, and one or more hydrophobic structural units.
11 . The electrode of claim 10 , wherein the hydrophilic structural units are derived from monomers comprising the group consisting of a carboxylic acid-containing monomer, an amide-containing monomer and combinations thereof; wherein the carboxylic acid-containing monomer is in the form of a carboxylic acid, a carboxylic acid salt, a carboxylic acid derivative or a combination thereof; and wherein the proportion of the hydrophilic structural units in the binder is from about 10% to about 90% by mole, based on the total number of moles of monomeric units in the binder.
12 . The electrode of claim 10 , wherein the hydrophobic structural units are derived from monomers comprising a nitrile-containing monomer, and wherein the proportion of the hydrophobic structural units in the binder is from about 10% to about 90% by mole, based on the total number of moles of monomeric units in the binder.
13 . The electrode of claim 1 , further comprising a conductive agent that is selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nano-fibers, graphitized carbon flake, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon and combinations thereof.
14 . The electrode of claim 1 , wherein the proportion of the additive in the electrode layer is from about 0.1% to about 5% by weight, based on the total weight of the electrode layer.
15 . The electrode of claim 1 , wherein the amount of the binder and the conductive agent in the electrode layer is independently from about 0.5% to about 5% by weight, based on the total weight of the electrode layer.
16 . An electrode slurry for a secondary battery, comprising an electrode active material, a binder, an additive and a solvent, wherein the additive satisfies general formula (1).
17 . The electrode slurry of claim 16 , wherein the solvent is water.
18 . The electrode slurry of claim 16 , wherein the proportion of the additive in the electrode slurry is from about 0.1% to about 5% by weight, based on the total weight of the solid content of the electrode slurry.
19 . The electrode slurry of claim 16 , wherein the amount of the electrode active material in the electrode slurry is from about 20% to about 80% by weight, based on the total weight of the electrode slurry.
20 . A secondary battery comprising the electrode of claim 1 .